Nitrocellulose solution



Patented Apr. 23, 1940 v I 2,198,173

UNITED, STATES PATENT OFFICE y.

NITROCELLULOS E SOLUTION Leonard P. Moore and Richard 0. Roblin, Jr.,

Stamford, Conn, assignors to American Cyanamid Company, New York, N. Y.,a corporation of Maine No Drawing. Application June 14, 1939, Serial No.279,140

10 Claims. (Cl. 134-79) This invention relates to a nitrocellulose slu-As illustrating the practice of this invention, tion and a method ofmaking the same. a clear lacquer was employed of the following It isknown that Whenever any nitrocellulose composition: V solution ismadeup, the initial viscosity is high EXAMPLE I and on agmg, the viscositydrops to some con- G stant value. The rate of drop is important and 1 ii rams the initial viscosity is a measure to some extent /2nitrocellulose 70% m alcohol 73 p of the strength of the solvent, a highviscosity fl 50% m toluol 300 for a given percent solids indicating aweak Dlbmyl phthalate 15 1 t l Butyl acetate 96.75 10 Lactate esters,such as the ethyl and butyl Butanol compounds, are employed as highboiling solvents T011101 1725 in nitrocellulose lacquers for the purposeof reg- Ethyl acetate ulating the rate of evaporation of the liquid in-23 alcohol gredients and controlling the final character of v 15 thefilm. They (10 not appreciably lower the 111- NA non-drying oil modifiedglycerol phthalate resin used as a plasticizim resin withnitrocellulose, a product Ina} vlscoslty of It IS readlly seen of theAmerican Cyamamid ta Chemical Corporation. No therefore, that inapplying a freshly prepared modified glycerol phthalate resins ofthisclass have come to the attention of the applicants which are notcompatible lacqufar of thls type conslderalb 1e m 1s neces with dimethylcyanamide or diethyl cyanamide.) sary in order to lower the v1scos1ty ofthe solution to suit conditions of application. As a re- The abovelacquer may be prepared by any of sult, more coats are required toproduce the dethe commonly employed methods Such as fi t sired fimsh'dispersing the nitrocellulose in a suitable portion 1 a 1 g to the ofthe solvent. This intermediate is then placed r ac e es ers m plgmen e mmce u 038 acquers in an ordinary mixer together with the remainingphenomenon which may be the result of mixture is thoroughly agltateduntil a homodrolysis of the ester and subsequent precipitageneous tionof zinc soaps, manifests itself in one or more The fonowmg vlscosltydetermmamons were 50 forms, such as an increase in the viscosity ofmadeW1thaStandardN-4Frd The read the lacquer, formation of largeparticles or 3%.. ings are in seconds, taken at a temperature ofglomerates and 1 of film 1 25 C. In each determination, a mixture of 16A principal object of the present invention is aims of the high-boiling501mm and 200 grams to provide a nitrocellulose solution ofsubstantialof the clear lacquer prepared as above, wavsvthor' 35 1y 10Winitial Viscosity Another object is the oughly agitated in an ordinarymixer until a uniprovision of a nitrocellulose solution; the viscosityform product was obtamedof which does not change appreciably on aging.

A further object is the provision of a nitrocellu- Table I 40 losesolution containing a high boiling solvent which insures elimination oflivering when pig- Et y BR15571130- c i de ments are incorporatedtherein. Other objects Timein hows i W019i;

will become apparent as the description of the inacque q lacquer 4E5vention proceeds.

These objects may be accomplished by incorg g gig porating, by anysuitable means in a nitrocellulose 41- 6 46. 0 29. 0 solution, asubstance chosen from the group congig sisting of dimethyl cyanamide anddiethyl cy- 5O anamide as hereinafter more fully described.

Table II Table IV Diethyl Dimethyl Dimethyl cyanamide cyanamide Time indays 3 Tlmem hours clear lacquer clear lacquer a g gf run No. 1 run No.2 a q 9 29 29 i From the viscosity readings given in these ta- 29 29bles, it is readily seen that in the ethyl lactate- Referring to TableI, it will be seen that the three lacquers approach a constant viscosityat approximately the same rate which means that the aging properties aresimilar. However, the initial viscosity is considerably lower, and thetotal decrease in viscosity is least for the lacquer containing diethylcyanamide.

Referring to Table II, it is readily seen that the initial viscosity ofthe lacquer containing the dimethyl cyanamide is much lower than thatobtained for the lacquers containing the lactate solvents in Table I,and that the viscosity does not change appreciably as the lacquer isaged.

These viscosity determinations indicate that the dimethyl and diethylcyanamides are more powerful solvents for nitrocellulose than either theethyl or butyl lactates and as a result, a better dispersion of thenitrocellulose is obtained.

In determining the effect of incorporating a high-boilingsolvent such asethyl lactate or diethyl cyanamide in a pigmented nitrocellulose lacquerin regard to livering tendencies, lacquers of the composition given inExamples II and III were prepared.

EXAMPLE II Grams /2 sec. nitrocellulose, 70% in alcohol 21.2 Damar gum19.8 Dibutyl phthalate 8.5 Zinc oxide 31.7 Ethyl lactate 42.5 Naphtha55.3 Xylol- 7.9 Ethyl alcohol 4.3

EXAMPLE III Grams sec. nitrocellulose, 70% in alcohol 21.2 Damar gum19.8 Dibutyl phthalate 8.5 Zinc oxide 31.7 Diethyl cyanamide 42.5

Naphtha 55.3 Xylol 7.9 Ethyl alcohol 4.3

These lacquers were prepared in a manner similar to the method describedunder Example I.

The following viscosity determinations were made using a standard No. 4Ford Cup. The readings are in seconds taken at a temperature of 25 C.

Table III Ethyl lactate pig- Tmle m days merited lacquer Thickencd to agel.

pigmented lacquer a livering condition occurred causing a gradualincrease in viscosity until the mass thickened to a gel, whereas in thediethyl cyanamide-pigmented lacquer, a low initial viscosity resultedwhich gradually decreased to a constant value showing that a stablecomposition was obtained.

It is to be understood that the lacquers utilized in the above examplesare typical compositions and that the types and proportions ofingredients shown may be varied over a considerable range and asubstitution of an equivalent material or a change in proportions tosuit the conditions of application or other special requirements isconsidered within the ordinary practice of one skilled in the art.

Optimum conditions are obtained when the high-boiling solvent, namelydimethyl cyanamide or diethyl cyanamide, is utilized within the range ofone to twenty-five percent by Weight of the nitrocellulose solution. 8%is a preferredproportion.

Although the typical lacquers shown above consist, in addition to thenitrocellulose and highboiliug solvent, of other ingredients such as aresin, plasticizer, diluents and low-boiling solvents, this invention isto be construed broadly as including a solution of nitrocellulose ineither of the high-boiling solvents, namely dimethyl cyanamide ordiethyl cyanamide,

Dialkyl cyanamides higher than the dimethyl and diethyl compounds are ingeneral unsatisfactory as solvents for use in nitrocellulose lacquersdue to their high boiling points.

Nitrocellulose lacquers prepared in accordance with this invention maybe utilized for general industrial finishing and are of particular meritWhere extraordinary lustre and smoothness in the surface of the film aredesired.

When tested at 78 F. and 50% relative humidity, the blush resistance ofa given lacquer containing ethyl lactate is substantially improved ifthe ethyl lactate is replaced by an equal weight of diethyl cyanamide.

An important advantage in this invention is that a nitrocellulosesolution of low initial viscosity may be obtained which does not changeappreciably on aging and which does not require the amount of dilutionto suit conditions of application that is needed with similar knowncompoby controlling the type of flow and character of the film.

While the invention has been described with particular. reference tospecific embodiments, it

is to be understood that it is not to be limited thereto, but is to beconstrued broadly and restricted solely by the scope of the appendedclaims.

We claim:

1. A solution of nitrocellulose including a substance selected from thegroup consisting of dimethyl cyanamide and diethyl cyanamide.

2. A lacquer including nitrocellulose, a substance selected from thegroup consisting of dimethyl cyanamide and diethyl cyanamide, a resinwhich can be used to plasticize nitrocellulose and which is compatiblewith dimethyl cyananiide or diethyl cyanamide, a plasticizer and asolvent.

3. A lacquer including nitrocellulose, a substance selected from thegroup consisting of dimethyl cyanarnide and diethyl cyanamide, a resinwhich can be used to plasticize nitrocellulose and which is compatiblewith dimethyl cyanamide or diethyl cyanamide, a plasticizer, a solventand a diluent.

4. Composition of claim 1 in which the cyanamide is present in theproportion of 8 per cent by weight of the whole.

5. Composition of claim 1 in which the cyanamide is present within therange of 1 to 25 per cent by Weight of the whole.

6. Composition of claim 2 in which the cyanamide is present in theproportion of 8 per cent by Weight of the whole.

'7. Composition of claim 2 in which the cyanamide is present within therange of 1 to 25 per cent by weight of the whole.

8. A method .of lowering the viscosity of a nitrocellulose solutionwhich includes adding therer to a substance chosen. from the groupconsisting of dimethyl cyanamide and diethyl cyanamide. 9. Method ofclaim 8 in which the cyanamide is present in the proportion of 8 percent by weight of the whole.

10. Method of claim 8 in wich the cyanamide is present within the rangeof 1 to 25 per cent by weight of the whole.

LEONARD P. MOORE. RICHARD O. ROBLIN, JR.

